Underwater vehicles (such as floats) may be used to measure physical and chemical properties of the ocean, detect underwater objects, and image seafloors or lakebeds. Various sensors such as pressure sensors, chemical sensors, temperature sensors, and sonars may be disposed on an underwater vessel. The underwater vessel may be tethered/towed from a platform, such as a ship, anchored to the hull of the ship, or may be an unmanned underwater vehicle (UUV) or autonomous underwater vehicle (AUV).